1. Field of the Invention
This invention relates generally to back flow check valves for use with liquid flow in administration structures for medical purposes.
2. Description of the Prior Art
A common problem of conventional type devices is that the check valves fail to function as positively and quickly as desired. Also, in hospitals and pharmacies hypodermic syringes are frequently used in the transfer of liquid medicines. Commonly, syringe pumping systems having two check valves have been used to pump a measured dose of dilutant or medicament to a series of further receptacles, or, in some cases, even into a patient. However, a common problem with such syringe pumping systems arises in the check valve system. Numerous types of check valves have been employed in the past; however, improvement still has been desired.
Existing prior art patents which may be pertinent to the present invention are as follows:
U.S. Pat. No. 3,572,375--3/23/71--Rosenberg PA1 U.S. Pat. No. 3,710,942--1/16/73--Rosenberg PA1 U.S. Pat. No. 3,886,937--6/3/75--Bobo et al. PA1 U.S. Pat. No. 4,084,606--4/18/78--Mittleman PA1 U.S. Pat. No. 4,210,173--7/1/80--Choksi et al. PA1 U.S. Pat. No. 4,246,932--1/27/81--Raines
U.S. Pat. No. 4,246,932 is by the same inventor as the present invention, and works in a similar manner thereto. However, the dual check valves therein are in co-planar relationship rather than co-axial relationship as in the present invention. The improvement of the present invention offers a number of desirable benefits over that of the inventor's prior device.
The Bobo et al. patent discloses a common administration system as is conventional, with typical check valve arrangement as used therein.
The Rosenberg patents show typical dual check valve assemblies which are substantially different from that of the present invention.
The Choksi et al. patent shows another similar dual check valve arrangement for use in a pumping system. However, in this arrangement, one check valve has a very heavy pressure, while the other one employs a light pressure.
The Mittleman patent is another dual check valve arrangement employing an umbrella valve and a duck bill valve.
None of the known prior art devices offer the new and novel features of the present invention.